1. Field of the Invention
The present invention relates to a device and a method for detecting the spatial position of the optical axis of the eye of a human or animal subject and for centering a reference system in relation to the optical axis, having at least one light source, which emits a parallel light beam bundle, a positioning region for the subject provided opposite the light source, means for relative position orientation of the parallel light beam bundle in relation to the eye of the subject, and at least one detector unit for detecting reflection events caused in and on the eye by the parallel light beam bundle.
2. Description of the Prior Art
Devices of the species described above are predominantly used in the field of ophthalmology, particularly for correcting the defective sight of an eye using a laser treatment system, particularly an excimer laser, to provide a targeted material removal on or inside the cornea, to achieve a desired change of the corneal curvature and a correction of the optical action of the cornea connected thereto.
The photorefractive correction of defective sight has been a recognized and very effective method for correcting vision errors for years. In the meantime, all types of defective sight such as nearsightedness (myopia), farsightedness (hyperopia), and corneal curvatures (astigmatism) have been treated very successfully using appropriately equipped laser systems. A requirement for successful treatment requires exact positioning of the treatment laser beam in relation to the cornea to be treated.
With increasing precision of the excimer laser systems and the precision of the diagnostic methods available, exact positioning of the treatment laser beam at the location of the cornea gains ever greater significance. A few years ago, the photorefractive correction of defective sight was modified by the simple use of the spectacle prescription as starting information in such a way that the spatially resolved aberrations of the entire system of the eye were measured using wavefront technology and the topographic properties of the cornea, and a corresponding correction guideline for the treatment laser beam was prepared.
It is a direct consequence that with the significant increase of detailed information available to the photorefractive correction, precise positioning of the eye to be treated and/or the treatment at the location of the cornea gains significance.
Treatment laser systems of this type are generally supported by eye tracker systems, which are based on greatly varying method technologies. With the aid of systems of this type, position changes of the eye in the magnitude of less than 100 μm may be recognized.
An essential requirement for successful correction of defective sight is thus precise orientation and positioning of the treatment laser beam in relation to the eye to be treated and its optical axis, and/or the optical axes of its refractive partial faces. The practice typical until now for adjusting a treatment laser beam in relation to the eye was performed up to this point in relation to the pupil center or purely subjectively by the treating physician, who oriented himself either on unchanging eye features or manually adjusted the treatment laser beam as a function of light reflections occurring on or in the eye. All laser-supported refractive surgery methods known up to this point for optimized correction of defective sight in the eye therefore lack an objectively repeatable adjustment of the treatment laser beam in relation to the eye to be treated and its optical axis, and/or the optical axes of its refractive partial faces.